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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 7.9 xx-xxx-09  Version 8.21
5    ------------
6    
7    1.  Updating the JIT compiler.
8    
9    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
10        are added as well.
11    
12    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
13        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
14        calling _pcre_jit_exec. Some extra comments are added.
15    
16    4.  Mark settings inside atomic groups that do not contain any capturing
17        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
18        was introduced by change 18 for 8.20.
19    
20    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
21        ECMA-262 standard.
22    
23    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
24        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
25        This bug was probably introduced by change 9 of 8.13.
26    
27    7.  While fixing 6 above, I noticed that a number of other items were being
28        incorrectly rejected as "not fixed length". This arose partly because newer
29        opcodes had not been added to the fixed-length checking code. I have (a)
30        corrected the bug and added tests for these items, and (b) arranged for an
31        error to occur if an unknown opcode is encountered while checking for fixed
32        length instead of just assuming "not fixed length". The items that were
33        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
34        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
35        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
36    
37    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
38        being incorrectly compiled and would have given unpredicatble results.
39    
40    9.  A possessively repeated subpattern with minimum repeat count greater than
41        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
42        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
43        the first (A) could occur when it should not.
44    
45    10. Add a cast and remove a redundant test from the code.
46    
47    11. JIT should use pcre_malloc/pcre_free for allocation.
48    
49    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
50        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
51        is anything other than /usr, -L is still shown).
52    
53    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
54    
55    14. Perl does not support \N without a following name in a [] class; PCRE now
56        also gives an error.
57    
58    15. If a forward reference was repeated with an upper limit of around 2000,
59        it caused the error "internal error: overran compiling workspace". The
60        maximum number of forward references (including repeats) was limited by the
61        internal workspace, and dependent on the LINK_SIZE. The code has been
62        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
63        the default depends on LINK_SIZE. There is a new upper limit (for safety)
64        of around 200,000 forward references. While doing this, I also speeded up
65        the filling in of repeated forward references.
66    
67    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
68        incorrectly expecting the subject to contain another "a" after the start.
69    
70    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
71        in the match, the SKIP should be ignored. This was not happening; instead
72        the SKIP was being treated as NOMATCH. For patterns such as
73        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
74        tested.
75    
76    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
77        now much more compatible with Perl, in particular in cases where the result
78        is a non-match for a non-anchored pattern. For example, if
79        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
80        "m", where previously it did not return a name. A side effect of this
81        change is that for partial matches, the last encountered mark name is
82        returned, as for non matches. A number of tests that were previously not
83        Perl-compatible have been moved into the Perl-compatible test files. The
84        refactoring has had the pleasing side effect of removing one argument from
85        the match() function, thus reducing its stack requirements.
86    
87    19. If the /S+ option was used in pcretest to study a pattern using JIT,
88        subsequent uses of /S (without +) incorrectly behaved like /S+.
89    
90    21. Retrieve executable code size support for the JIT compiler and fixing
91        some warnings.
92    
93    
94    Version 8.20 21-Oct-2011
95    ------------------------
96    
97    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
98        a POSIX class. After further experiments with Perl, which convinced me that
99        Perl has bugs and confusions, a closing square bracket is no longer allowed
100        in a POSIX name. This bug also affected patterns with classes that started
101        with full stops.
102    
103    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
104        captured substring, but while checking the failing first alternative,
105        substring 1 is temporarily captured. If the output vector supplied to
106        pcre_exec() was not big enough for this capture, the yield of the function
107        was still zero ("insufficient space for captured substrings"). This cannot
108        be totally fixed without adding another stack variable, which seems a lot
109        of expense for a edge case. However, I have improved the situation in cases
110        such as /(a)(b)x|abc/ matched against "abc", where the return code
111        indicates that fewer than the maximum number of slots in the ovector have
112        been set.
113    
114    3.  Related to (2) above: when there are more back references in a pattern than
115        slots in the output vector, pcre_exec() uses temporary memory during
116        matching, and copies in the captures as far as possible afterwards. It was
117        using the entire output vector, but this conflicts with the specification
118        that only 2/3 is used for passing back captured substrings. Now it uses
119        only the first 2/3, for compatibility. This is, of course, another edge
120        case.
121    
122    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
123        main code base, and can be used by building with --enable-jit. When this is
124        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
125        runtime --no-jit option is given.
126    
127    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
128        ovector, the return from the function was zero, implying that there were
129        other matches that did not fit. The correct "exactly full" value is now
130        returned.
131    
132    6.  If a subpattern that was called recursively or as a subroutine contained
133        (*PRUNE) or any other control that caused it to give a non-standard return,
134        invalid errors such as "Error -26 (nested recursion at the same subject
135        position)" or even infinite loops could occur.
136    
137    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
138        computing the minimum length on reaching *ACCEPT, and so ended up with the
139        wrong value of 1 rather than 0. Further investigation indicates that
140        computing a minimum subject length in the presence of *ACCEPT is difficult
141        (think back references, subroutine calls), and so I have changed the code
142        so that no minimum is registered for a pattern that contains *ACCEPT.
143    
144    8.  If (*THEN) was present in the first (true) branch of a conditional group,
145        it was not handled as intended. [But see 16 below.]
146    
147    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
148        Sheri Pierce.
149    
150    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
151        the first byte in a match must be "a".
152    
153    11. Change 17 for 8.13 increased the recursion depth for patterns like
154        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
155        pattern contains any instances of (*THEN). If it does not, the old
156        optimizations are restored. It would be nice to do this on a per-group
157        basis, but at the moment that is not feasible.
158    
159    12. In some environments, the output of pcretest -C is CRLF terminated. This
160        broke RunTest's code that checks for the link size. A single white space
161        character after the value is now allowed for.
162    
163    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
164        For "fr", it uses the Windows-specific input and output files.
165    
166    14. If (*THEN) appeared in a group that was called recursively or as a
167        subroutine, it did not work as intended. [But see next item.]
168    
169    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
170        pattern fragments (but not containing any | characters). If A and B are
171        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
172        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
173        D. In other words, Perl considers parentheses that do not contain any |
174        characters to be part of a surrounding alternative, whereas PCRE was
175        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
176        differently. PCRE now behaves in the same way as Perl, except in the case
177        of subroutine/recursion calls such as (?1) which have in any case always
178        been different (but PCRE had them first :-).
179    
180    16. Related to 15 above: Perl does not treat the | in a conditional group as
181        creating alternatives. Such a group is treated in the same way as an
182        ordinary group without any | characters when processing (*THEN). PCRE has
183        been changed to match Perl's behaviour.
184    
185    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
186        RunGrepTest script failed.
187    
188    18. Change 22 for version 13 caused atomic groups to use more stack. This is
189        inevitable for groups that contain captures, but it can lead to a lot of
190        stack use in large patterns. The old behaviour has been restored for atomic
191        groups that do not contain any capturing parentheses.
192    
193    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
194        suppress the check for a minimum subject length at run time. (If it was
195        given to pcre_exec() or pcre_dfa_exec() it did work.)
196    
197    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
198        fail to work when decoding hex characters in data strings in EBCDIC
199        environments.
200    
201    21. It appears that in at least one Mac OS environment, the isxdigit() function
202        is implemented as a macro that evaluates to its argument more than once,
203        contravening the C 90 Standard (I haven't checked a later standard). There
204        was an instance in pcretest which caused it to go wrong when processing
205        \x{...} escapes in subject strings. The has been rewritten to avoid using
206        things like p++ in the argument of isxdigit().
207    
208    
209    Version 8.13 16-Aug-2011
210    ------------------------
211    
212    1.  The Unicode data tables have been updated to Unicode 6.0.0.
213    
214    2.  Two minor typos in pcre_internal.h have been fixed.
215    
216    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
217        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
218        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
219    
220    4.  There were a number of related bugs in the code for matching backrefences
221        caselessly in UTF-8 mode when codes for the characters concerned were
222        different numbers of bytes. For example, U+023A and U+2C65 are an upper
223        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
224        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
225        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
226        2-byte code at the end of the subject (it thought there wasn't enough data
227        left).
228    
229    5.  Comprehensive information about what went wrong is now returned by
230        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
231        as the output vector has at least 2 elements. The offset of the start of
232        the failing character and a reason code are placed in the vector.
233    
234    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
235        now returned is for the first byte of the failing character, instead of the
236        last byte inspected. This is an incompatible change, but I hope it is small
237        enough not to be a problem. It makes the returned offset consistent with
238        pcre_exec() and pcre_dfa_exec().
239    
240    7.  pcretest now gives a text phrase as well as the error number when
241        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
242        failure, the offset and reason code are output.
243    
244    8.  When \R was used with a maximizing quantifier it failed to skip backwards
245        over a \r\n pair if the subsequent match failed. Instead, it just skipped
246        back over a single character (\n). This seems wrong (because it treated the
247        two characters as a single entity when going forwards), conflicts with the
248        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
249        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
250        has been changed.
251    
252    9.  Some internal refactoring has changed the processing so that the handling
253        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
254        time (the PCRE_DOTALL option was changed this way some time ago: version
255        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
256        which was always a bit of a fudge. It also means that there is one less
257        argument for the match() function, which reduces its stack requirements
258        slightly. This change also fixes an incompatibility with Perl: the pattern
259        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
260    
261    10. More internal refactoring has drastically reduced the number of recursive
262        calls to match() for possessively repeated groups such as (abc)++ when
263        using pcre_exec().
264    
265    11. While implementing 10, a number of bugs in the handling of groups were
266        discovered and fixed:
267    
268        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
269        (a|)*(?1) gave a compile-time internal error.
270        ((a|)+)+  did not notice that the outer group could match an empty string.
271        (^a|^)+   was not marked as anchored.
272        (.*a|.*)+ was not marked as matching at start or after a newline.
273    
274    12. Yet more internal refactoring has removed another argument from the match()
275        function. Special calls to this function are now indicated by setting a
276        value in a variable in the "match data" data block.
277    
278    13. Be more explicit in pcre_study() instead of relying on "default" for
279        opcodes that mean there is no starting character; this means that when new
280        ones are added and accidentally left out of pcre_study(), testing should
281        pick them up.
282    
283    14. The -s option of pcretest has been documented for ages as being an old
284        synonym of -m (show memory usage). I have changed it to mean "force study
285        for every regex", that is, assume /S for every regex. This is similar to -i
286        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
287        using it. It makes it easier to run collections of tests with and without
288        study enabled, and thereby test pcre_study() more easily. All the standard
289        tests are now run with and without -s (but some patterns can be marked as
290        "never study" - see 20 below).
291    
292    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
293        restoration of the capturing data to the outer values was not happening
294        correctly.
295    
296    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
297        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
298        pattern had matched an empty string, and so incorrectly returned a no
299        match.
300    
301    17. There was optimizing code for the last branch of non-capturing parentheses,
302        and also for the obeyed branch of a conditional subexpression, which used
303        tail recursion to cut down on stack usage. Unfortunately, now that there is
304        the possibility of (*THEN) occurring in these branches, tail recursion is
305        no longer possible because the return has to be checked for (*THEN). These
306        two optimizations have therefore been removed. [But see 8.20/11 above.]
307    
308    18. If a pattern containing \R was studied, it was assumed that \R always
309        matched two bytes, thus causing the minimum subject length to be
310        incorrectly computed because \R can also match just one byte.
311    
312    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
313        was incorrectly computed.
314    
315    20. If /S is present twice on a test pattern in pcretest input, it now
316        *disables* studying, thereby overriding the use of -s on the command line
317        (see 14 above). This is necessary for one or two tests to keep the output
318        identical in both cases.
319    
320    21. When (*ACCEPT) was used in an assertion that matched an empty string and
321        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
322    
323    22. When an atomic group that contained a capturing parenthesis was
324        successfully matched, but the branch in which it appeared failed, the
325        capturing was not being forgotten if a higher numbered group was later
326        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
327        group 1 to "a", when in fact it should be unset. This applied to multi-
328        branched capturing and non-capturing groups, repeated or not, and also to
329        positive assertions (capturing in negative assertions does not happen
330        in PCRE) and also to nested atomic groups.
331    
332    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
333        subject after a captured substring, to make it easier to tell which of a
334        number of identical substrings has been captured.
335    
336    24. The way atomic groups are processed by pcre_exec() has been changed so that
337        if they are repeated, backtracking one repetition now resets captured
338        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
339        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
340        "aaa". Previously, it would have been "a". As part of this code
341        refactoring, the way recursive calls are handled has also been changed.
342    
343    25. If an assertion condition captured any substrings, they were not passed
344        back unless some other capturing happened later. For example, if
345        (?(?=(a))a) was matched against "a", no capturing was returned.
346    
347    26. When studying a pattern that contained subroutine calls or assertions,
348        the code for finding the minimum length of a possible match was handling
349        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
350        group 1 called group 2 while simultaneously a separate group 2 called group
351        1). A stack overflow occurred in this case. I have fixed this by limiting
352        the recursion depth to 10.
353    
354    27. Updated RunTest.bat in the distribution to the version supplied by Tom
355        Fortmann. This supports explicit test numbers on the command line, and has
356        argument validation and error reporting.
357    
358    28. An instance of \X with an unlimited repeat could fail if at any point the
359        first character it looked at was a mark character.
360    
361    29. Some minor code refactoring concerning Unicode properties and scripts
362        should reduce the stack requirement of match() slightly.
363    
364    30. Added the '=' option to pcretest to check the setting of unused capturing
365        slots at the end of the pattern, which are documented as being -1, but are
366        not included in the return count.
367    
368    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
369        compiled something random. Now it gives a compile-time error (as does
370        Perl).
371    
372    32. A *MARK encountered during the processing of a positive assertion is now
373        recorded and passed back (compatible with Perl).
374    
375    33. If --only-matching or --colour was set on a pcregrep call whose pattern
376        had alternative anchored branches, the search for a second match in a line
377        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
378        matched the line "0102" twice. The same bug affected patterns that started
379        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
380        twice.
381    
382    34. Previously, PCRE did not allow quantification of assertions. However, Perl
383        does, and because of capturing effects, quantifying parenthesized
384        assertions may at times be useful. Quantifiers are now allowed for
385        parenthesized assertions.
386    
387    35. A minor code tidy in pcre_compile() when checking options for \R usage.
388    
389    36. \g was being checked for fancy things in a character class, when it should
390        just be a literal "g".
391    
392    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
393        appearance of a nested POSIX class supersedes an apparent external class.
394        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
395        unescaped square brackets may also appear as part of class names. For
396        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
397        more like Perl. (But see 8.20/1 above.)
398    
399    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
400        was because it thought it was \N{name}, which is not supported).
401    
402    39. Add minix to OS list not supporting the -S option in pcretest.
403    
404    40. PCRE tries to detect cases of infinite recursion at compile time, but it
405        cannot analyze patterns in sufficient detail to catch mutual recursions
406        such as ((?1))((?2)). There is now a runtime test that gives an error if a
407        subgroup is called recursively as a subpattern for a second time at the
408        same position in the subject string. In previous releases this might have
409        been caught by the recursion limit, or it might have run out of stack.
410    
411    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
412        happen only once. PCRE was, however incorrectly giving a compile time error
413        "recursive call could loop indefinitely" because it cannot analyze the
414        pattern in sufficient detail. The compile time test no longer happens when
415        PCRE is compiling a conditional subpattern, but actual runaway loops are
416        now caught at runtime (see 40 above).
417    
418    42. It seems that Perl allows any characters other than a closing parenthesis
419        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
420        has been changed to be the same.
421    
422    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
423        as not to get warnings when autogen.sh is called. Also changed
424        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
425    
426    44. To help people who use pcregrep to scan files containing exceedingly long
427        lines, the following changes have been made:
428    
429        (a) The default value of the buffer size parameter has been increased from
430            8K to 20K. (The actual buffer used is three times this size.)
431    
432        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
433            PCRE is built.
434    
435        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
436            to be set at run time.
437    
438        (d) Numerical values in pcregrep options can be followed by K or M, for
439            example --buffer-size=50K.
440    
441        (e) If a line being scanned overflows pcregrep's buffer, an error is now
442            given and the return code is set to 2.
443    
444    45. Add a pointer to the latest mark to the callout data block.
445    
446    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
447        partial match of an empty string instead of no match. This was specific to
448        the use of ".".
449    
450    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
451        complete match instead of a partial match. This bug was dependent on both
452        the PCRE_UTF8 and PCRE_DOTALL options being set.
453    
454    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
455        starting byte set, because \b was not being ignored.
456    
457    
458    Version 8.12 15-Jan-2011
459    ------------------------
460    
461    1.  Fixed some typos in the markup of the man pages, and wrote a script that
462        checks for such things as part of the documentation building process.
463    
464    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
465        --match-limit and --recursion-limit options (added for 8.11). In
466        particular, this made one of the standard tests fail. (The integer value
467        went into the wrong half of a long int.)
468    
469    3.  If the --colour option was given to pcregrep with -v (invert match), it
470        did strange things, either producing crazy output, or crashing. It should,
471        of course, ignore a request for colour when reporting lines that do not
472        match.
473    
474    4.  Another pcregrep bug caused similar problems if --colour was specified with
475        -M (multiline) and the pattern match finished with a line ending.
476    
477    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
478        matched in multiline mode, the following line was shown as part of the
479        match. This seems wrong, so I have changed it.
480    
481    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
482        the check for further matches in the same line (so they could be coloured)
483        to overrun the end of the current line. If another match was found, it was
484        incorrectly shown (and then shown again when found in the next line).
485    
486    7.  If pcregrep was compiled under Windows, there was a reference to the
487        function pcregrep_exit() before it was defined. I am assuming this was
488        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
489        reported by a user. I've moved the definition above the reference.
490    
491    
492    Version 8.11 10-Dec-2010
493    ------------------------
494    
495    1.  (*THEN) was not working properly if there were untried alternatives prior
496        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
497        backtracked to try for "b" instead of moving to the next alternative branch
498        at the same level (in this case, to look for "c"). The Perl documentation
499        is clear that when (*THEN) is backtracked onto, it goes to the "next
500        alternative in the innermost enclosing group".
501    
502    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
503        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
504        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
505        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
506        (*THEN).
507    
508    3.  If \s appeared in a character class, it removed the VT character from
509        the class, even if it had been included by some previous item, for example
510        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
511        of \s, but is part of the POSIX "space" class.)
512    
513    4.  A partial match never returns an empty string (because you can always
514        match an empty string at the end of the subject); however the checking for
515        an empty string was starting at the "start of match" point. This has been
516        changed to the "earliest inspected character" point, because the returned
517        data for a partial match starts at this character. This means that, for
518        example, /(?<=abc)def/ gives a partial match for the subject "abc"
519        (previously it gave "no match").
520    
521    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
522        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
523        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
524        has an implication that the given string is incomplete (because a partial
525        match is preferred over a full match). For this reason, these items now
526        give a partial match in this situation. [Aside: previously, the one case
527        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
528        match rather than a full match, which was wrong by the old rules, but is
529        now correct.]
530    
531    6.  There was a bug in the handling of #-introduced comments, recognized when
532        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
533        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
534        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
535        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
536        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
537        places in pcre_compile().
538    
539    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
540        comments when looking ahead for named forward references to subpatterns,
541        the only newline sequence it recognized was NL. It now handles newlines
542        according to the set newline convention.
543    
544    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
545        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
546        cater for a lack of strerror(). These oversights have been fixed.
547    
548    9.  Added --match-limit and --recursion-limit to pcregrep.
549    
550    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
551    
552    11. When the -o option was used, pcregrep was setting a return code of 1, even
553        when matches were found, and --line-buffered was not being honoured.
554    
555    12. Added an optional parentheses number to the -o and --only-matching options
556        of pcregrep.
557    
558    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
559        can match an empty string. The code to do it in pcretest and pcredemo
560        needed fixing:
561    
562        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
563            only one byte after an empty string match just before CRLF (this case
564            just got forgotten; "any" and "anycrlf" were OK).
565    
566        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
567            mode when an empty string match preceded an ASCII character followed by
568            a non-ASCII character. (The code for advancing by one character rather
569            than one byte was nonsense.)
570    
571        (c) The pcredemo.c sample program did not have any code at all to handle
572            the cases when CRLF is a valid newline sequence.
573    
574    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
575        as a starting offset was within the subject string. There is now a new
576        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
577        negative or greater than the length of the string. In order to test this,
578        pcretest is extended to allow the setting of negative starting offsets.
579    
580    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
581        starting offset points to the beginning of a UTF-8 character was
582        unnecessarily clumsy. I tidied it up.
583    
584    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
585        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
586    
587    17. Nobody had reported that the --include_dir option, which was added in
588        release 7.7 should have been called --include-dir (hyphen, not underscore)
589        for compatibility with GNU grep. I have changed it to --include-dir, but
590        left --include_dir as an undocumented synonym, and the same for
591        --exclude-dir, though that is not available in GNU grep, at least as of
592        release 2.5.4.
593    
594    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
595        characters from a string of bytes) have been redefined so as not to use
596        loops, in order to improve performance in some environments. At the same
597        time, I abstracted some of the common code into auxiliary macros to save
598        repetition (this should not affect the compiled code).
599    
600    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
601        compile-time error is now given if \c is not followed by an ASCII
602        character, that is, a byte less than 128. (In EBCDIC mode, the code is
603        different, and any byte value is allowed.)
604    
605    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
606        START_OPTIMIZE option, which is now allowed at compile time - but just
607        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
608        to pcregrep and other applications that have no direct access to PCRE
609        options. The new /Y option in pcretest sets this option when calling
610        pcre_compile().
611    
612    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
613        back references. Groups containing recursive back references were forced to
614        be atomic by that change, but in the case of named groups, the amount of
615        memory required was incorrectly computed, leading to "Failed: internal
616        error: code overflow". This has been fixed.
617    
618    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
619        pcretest.c, to avoid build problems in some Borland environments.
620    
621    
622    Version 8.10 25-Jun-2010
623    ------------------------
624    
625    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
626        THEN.
627    
628    2.  (*ACCEPT) was not working when inside an atomic group.
629    
630    3.  Inside a character class, \B is treated as a literal by default, but
631        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
632        causes the error). The code is unchanged, but I tidied the documentation.
633    
634    4.  Inside a character class, PCRE always treated \R and \X as literals,
635        whereas Perl faults them if its -w option is set. I have changed PCRE so
636        that it faults them when PCRE_EXTRA is set.
637    
638    5.  Added support for \N, which always matches any character other than
639        newline. (It is the same as "." when PCRE_DOTALL is not set.)
640    
641    6.  When compiling pcregrep with newer versions of gcc which may have
642        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
643        declared with attribute warn_unused_result" were given. Just casting the
644        result to (void) does not stop the warnings; a more elaborate fudge is
645        needed. I've used a macro to implement this.
646    
647    7.  Minor change to pcretest.c to avoid a compiler warning.
648    
649    8.  Added four artifical Unicode properties to help with an option to make
650        \s etc use properties (see next item). The new properties are: Xan
651        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
652    
653    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
654        use Unicode properties. (*UCP) at the start of a pattern can be used to set
655        this option. Modified pcretest to add /W to test this facility. Added
656        REG_UCP to make it available via the POSIX interface.
657    
658    10. Added --line-buffered to pcregrep.
659    
660    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
661        studied, and the match started with a letter with a code point greater than
662        127 whose first byte was different to the first byte of the other case of
663        the letter, the other case of this starting letter was not recognized
664        (#976).
665    
666    12. If a pattern that was studied started with a repeated Unicode property
667        test, for example, \p{Nd}+, there was the theoretical possibility of
668        setting up an incorrect bitmap of starting bytes, but fortunately it could
669        not have actually happened in practice until change 8 above was made (it
670        added property types that matched character-matching opcodes).
671    
672    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
673        possible starting bytes for non-anchored patterns.
674    
675    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
676        \R, and also a number of cases that involve Unicode properties, both
677        explicit and implicit when PCRE_UCP is set.
678    
679    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
680        input, it could crash or give wrong results if characters with values
681        greater than 0xc0 were present in the subject string. (Detail: it assumed
682        UTF-8 input when processing these items.)
683    
684    16. Added a lot of (int) casts to avoid compiler warnings in systems where
685        size_t is 64-bit (#991).
686    
687    17. Added a check for running out of memory when PCRE is compiled with
688        --disable-stack-for-recursion (#990).
689    
690    18. If the last data line in a file for pcretest does not have a newline on
691        the end, a newline was missing in the output.
692    
693    19. The default pcre_chartables.c file recognizes only ASCII characters (values
694        less than 128) in its various bitmaps. However, there is a facility for
695        generating tables according to the current locale when PCRE is compiled. It
696        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
697        characters, are recognized by isspace() and therefore were getting set in
698        these tables, and indeed these tables seem to approximate to ISO 8859. This
699        caused a problem in UTF-8 mode when pcre_study() was used to create a list
700        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
701        which of course cannot start UTF-8 characters. I have changed the code so
702        that only real ASCII characters (less than 128) and the correct starting
703        bytes for UTF-8 encodings are set for characters greater than 127 when in
704        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
705        altogether.)
706    
707    20. Added the /T option to pcretest so as to be able to run tests with non-
708        standard character tables, thus making it possible to include the tests
709        used for 19 above in the standard set of tests.
710    
711    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
712        reference to a subpattern the other side of a comment that contains an
713        opening parenthesis caused either an internal compiling error, or a
714        reference to the wrong subpattern.
715    
716    
717    Version 8.02 19-Mar-2010
718    ------------------------
719    
720    1.  The Unicode data tables have been updated to Unicode 5.2.0.
721    
722    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
723        configured.
724    
725    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
726        original author of that file, following a query about its status.
727    
728    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
729        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
730    
731    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
732        quantifier applied to a forward-referencing subroutine call, could compile
733        incorrect code or give the error "internal error: previously-checked
734        referenced subpattern not found".
735    
736    6.  Both MS Visual Studio and Symbian OS have problems with initializing
737        variables to point to external functions. For these systems, therefore,
738        pcre_malloc etc. are now initialized to local functions that call the
739        relevant global functions.
740    
741    7.  There were two entries missing in the vectors called coptable and poptable
742        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
743        I've fixed the data, and added a kludgy way of testing at compile time that
744        the lengths are correct (equal to the number of opcodes).
745    
746    8.  Following on from 7, I added a similar kludge to check the length of the
747        eint vector in pcreposix.c.
748    
749    9.  Error texts for pcre_compile() are held as one long string to avoid too
750        much relocation at load time. To find a text, the string is searched,
751        counting zeros. There was no check for running off the end of the string,
752        which could happen if a new error number was added without updating the
753        string.
754    
755    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
756    
757    11. \K was not working if it appeared in an atomic group or in a group that
758        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
759        \K is "not well defined" if used in an assertion. PCRE now accepts it if
760        the assertion is positive, but not if it is negative.
761    
762    12. Change 11 fortuitously reduced the size of the stack frame used in the
763        "match()" function of pcre_exec.c by one pointer. Forthcoming
764        implementation of support for (*MARK) will need an extra pointer on the
765        stack; I have reserved it now, so that the stack frame size does not
766        decrease.
767    
768    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
769        item in branch that calls a recursion is a subroutine call - as in the
770        second branch in the above example - was incorrectly given the compile-
771        time error "recursive call could loop indefinitely" because pcre_compile()
772        was not correctly checking the subroutine for matching a non-empty string.
773    
774    14. The checks for overrunning compiling workspace could trigger after an
775        overrun had occurred. This is a "should never occur" error, but it can be
776        triggered by pathological patterns such as hundreds of nested parentheses.
777        The checks now trigger 100 bytes before the end of the workspace.
778    
779    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
780    
781    
782    Version 8.01 19-Jan-2010
783    ------------------------
784    
785    1.  If a pattern contained a conditional subpattern with only one branch (in
786        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
787        computed the wrong minimum data length (which is of course zero for such
788        subpatterns). This could cause incorrect "no match" results.
789    
790    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
791        the pattern is reset in the first branch, pcre_compile() failed with
792        "internal error: code overflow at offset...". This happened only when
793        the reset was to the original external option setting. (An optimization
794        abstracts leading options settings into an external setting, which was the
795        cause of this.)
796    
797    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
798        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
799        assertion pattern did not match (meaning that the assertion was true), it
800        was incorrectly treated as false if the SKIP had been reached during the
801        matching. This also applied to assertions used as conditions.
802    
803    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
804        assertion subpattern, including such a pattern used as a condition,
805        unpredictable results occurred, instead of the error return
806        PCRE_ERROR_DFA_UITEM.
807    
808    5.  The C++ GlobalReplace function was not working like Perl for the special
809        situation when an empty string is matched. It now does the fancy magic
810        stuff that is necessary.
811    
812    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
813        removed. (These were left over from very, very early versions of PCRE.)
814    
815    7.  Some cosmetic changes to the code to make life easier when compiling it
816        as part of something else:
817    
818        (a) Change DEBUG to PCRE_DEBUG.
819    
820        (b) In pcre_compile(), rename the member of the "branch_chain" structure
821            called "current" as "current_branch", to prevent a collision with the
822            Linux macro when compiled as a kernel module.
823    
824        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
825            prevent a collision with the Linux macro when compiled as a kernel
826            module.
827    
828    8.  In pcre_compile() there are some checks for integer overflows that used to
829        cast potentially large values to (double). This has been changed to that
830        when building, a check for int64_t is made, and if it is found, it is used
831        instead, thus avoiding the use of floating point arithmetic. (There is no
832        other use of FP in PCRE.) If int64_t is not found, the fallback is to
833        double.
834    
835    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
836        2005 (difference between two addresses compared to an unsigned value).
837    
838    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
839        custom one, because of the following reported problem in Windows:
840    
841          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
842              under Win32.
843          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
844              therefore missing the function definition.
845          - The compiler thus generates a "C" signature for the test function.
846          - The linker fails to find the "C" function.
847          - PCRE fails to configure if asked to do so against libbz2.
848    
849    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
850        messages were output:
851    
852          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
853          rerunning libtoolize, to keep the correct libtool macros in-tree.
854          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
855    
856        I have done both of these things.
857    
858    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
859        most of the time, it *can* run out if it is given a pattern that contains a
860        runaway infinite recursion. I updated the discussion in the pcrestack man
861        page.
862    
863    13. Now that we have gone to the x.xx style of version numbers, the minor
864        version may start with zero. Using 08 or 09 is a bad idea because users
865        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
866        interpreted as invalid octal numbers. I've updated the previous comment in
867        configure.ac, and also added a check that gives an error if 08 or 09 are
868        used.
869    
870    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
871        causing partial matching to fail when the end of the subject matched \W
872        in a UTF-8 pattern where \W was quantified with a minimum of 3.
873    
874    15. There were some discrepancies between the declarations in pcre_internal.h
875        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
876        their definitions. The declarations used "const uschar *" and the
877        definitions used USPTR. Even though USPTR is normally defined as "const
878        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
879        reported that: "This difference in casting confuses some C++ compilers, for
880        example, SunCC recognizes above declarations as different functions and
881        generates broken code for hbpcre." I have changed the declarations to use
882        USPTR.
883    
884    16. GNU libtool is named differently on some systems. The autogen.sh script now
885        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
886        (FreeBSD).
887    
888    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
889        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
890        comment: "Figure out how to create a longlong from a string: strtoll and
891        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
892        instance, but it only takes 2 args instead of 3!"
893    
894    18. A subtle bug concerned with back references has been fixed by a change of
895        specification, with a corresponding code fix. A pattern such as
896        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
897        refers, was giving matches when it shouldn't. For example, xa=xaaa would
898        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
899        same bug. Such groups have to be quantified to be useful, or contained
900        inside another quantified group. (If there's no repetition, the reference
901        can never match.) The problem arises because, having left the group and
902        moved on to the rest of the pattern, a later failure that backtracks into
903        the group uses the captured value from the final iteration of the group
904        rather than the correct earlier one. I have fixed this in PCRE by forcing
905        any group that contains a reference to itself to be an atomic group; that
906        is, there cannot be any backtracking into it once it has completed. This is
907        similar to recursive and subroutine calls.
908    
909    
910    Version 8.00 19-Oct-09
911    ----------------------
912    
913    1.  The table for translating pcre_compile() error codes into POSIX error codes
914        was out-of-date, and there was no check on the pcre_compile() error code
915        being within the table. This could lead to an OK return being given in
916        error.
917    
918    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
919        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
920        in a Windows environment.
921    
922    3.  The pcregrep --count option prints the count for each file even when it is
923        zero, as does GNU grep. However, pcregrep was also printing all files when
924        --files-with-matches was added. Now, when both options are given, it prints
925        counts only for those files that have at least one match. (GNU grep just
926        prints the file name in this circumstance, but including the count seems
927        more useful - otherwise, why use --count?) Also ensured that the
928        combination -clh just lists non-zero counts, with no names.
929    
930    4.  The long form of the pcregrep -F option was incorrectly implemented as
931        --fixed_strings instead of --fixed-strings. This is an incompatible change,
932        but it seems right to fix it, and I didn't think it was worth preserving
933        the old behaviour.
934    
935    5.  The command line items --regex=pattern and --regexp=pattern were not
936        recognized by pcregrep, which required --regex pattern or --regexp pattern
937        (with a space rather than an '='). The man page documented the '=' forms,
938        which are compatible with GNU grep; these now work.
939    
940    6.  No libpcreposix.pc file was created for pkg-config; there was just
941        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
942    
943    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
944        when UCP support is not needed, by modifying the Python script that
945        generates it from Unicode data files. This should not matter if the module
946        is correctly used as a library, but I received one complaint about 50K of
947        unwanted data. My guess is that the person linked everything into his
948        program rather than using a library. Anyway, it does no harm.
949    
950    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
951        was a minimum greater than 1 for a wide character in a possessive
952        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
953        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
954        character. Chaos in the form of incorrect output or a compiling loop could
955        result.
956    
957    9.  The restrictions on what a pattern can contain when partial matching is
958        requested for pcre_exec() have been removed. All patterns can now be
959        partially matched by this function. In addition, if there are at least two
960        slots in the offset vector, the offset of the earliest inspected character
961        for the match and the offset of the end of the subject are set in them when
962        PCRE_ERROR_PARTIAL is returned.
963    
964    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
965        synonymous with PCRE_PARTIAL, for backwards compatibility, and
966        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
967        and may be more useful for multi-segment matching.
968    
969    11. Partial matching with pcre_exec() is now more intuitive. A partial match
970        used to be given if ever the end of the subject was reached; now it is
971        given only if matching could not proceed because another character was
972        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
973        string "Z", which now yields "no match" instead of "partial match". In the
974        case of pcre_dfa_exec(), "no match" is given if every matching path for the
975        final character ended with (*FAIL).
976    
977    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
978        if the pattern had a "must contain" character that was already found in the
979        earlier partial match, unless partial matching was again requested. For
980        example, with the pattern /dog.(body)?/, the "must contain" character is
981        "g". If the first part-match was for the string "dog", restarting with
982        "sbody" failed. This bug has been fixed.
983    
984    13. The string returned by pcre_dfa_exec() after a partial match has been
985        changed so that it starts at the first inspected character rather than the
986        first character of the match. This makes a difference only if the pattern
987        starts with a lookbehind assertion or \b or \B (\K is not supported by
988        pcre_dfa_exec()). It's an incompatible change, but it makes the two
989        matching functions compatible, and I think it's the right thing to do.
990    
991    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
992        so that the demonstration program is easily available in environments where
993        PCRE has not been installed from source.
994    
995    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
996        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
997        library.
998    
999    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
1000        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
1001        is not the first non-POSIX option to be added. Clearly some people find
1002        these options useful.
1003    
1004    17. If a caller to the POSIX matching function regexec() passes a non-zero
1005        value for nmatch with a NULL value for pmatch, the value of
1006        nmatch is forced to zero.
1007    
1008    18. RunGrepTest did not have a test for the availability of the -u option of
1009        the diff command, as RunTest does. It now checks in the same way as
1010        RunTest, and also checks for the -b option.
1011    
1012    19. If an odd number of negated classes containing just a single character
1013        interposed, within parentheses, between a forward reference to a named
1014        subpattern and the definition of the subpattern, compilation crashed with
1015        an internal error, complaining that it could not find the referenced
1016        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
1017        [The bug was that it was starting one character too far in when skipping
1018        over the character class, thus treating the ] as data rather than
1019        terminating the class. This meant it could skip too much.]
1020    
1021    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
1022        /g option in pcretest when the pattern contains \K, which makes it possible
1023        to have an empty string match not at the start, even when the pattern is
1024        anchored. Updated pcretest and pcredemo to use this option.
1025    
1026    21. If the maximum number of capturing subpatterns in a recursion was greater
1027        than the maximum at the outer level, the higher number was returned, but
1028        with unset values at the outer level. The correct (outer level) value is
1029        now given.
1030    
1031    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
1032        PCRE did not set those parentheses (unlike Perl). I have now found a way to
1033        make it do so. The string so far is captured, making this feature
1034        compatible with Perl.
1035    
1036    23. The tests have been re-organized, adding tests 11 and 12, to make it
1037        possible to check the Perl 5.10 features against Perl 5.10.
1038    
1039    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
1040        pattern matches a fixed length string. PCRE did not allow this; now it
1041        does. Neither allows recursion.
1042    
1043    25. I finally figured out how to implement a request to provide the minimum
1044        length of subject string that was needed in order to match a given pattern.
1045        (It was back references and recursion that I had previously got hung up
1046        on.) This code has now been added to pcre_study(); it finds a lower bound
1047        to the length of subject needed. It is not necessarily the greatest lower
1048        bound, but using it to avoid searching strings that are too short does give
1049        some useful speed-ups. The value is available to calling programs via
1050        pcre_fullinfo().
1051    
1052    26. While implementing 25, I discovered to my embarrassment that pcretest had
1053        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
1054        study optimizations had never been tested with that matching function.
1055        Oops. What is worse, even when it was passed study data, there was a bug in
1056        pcre_dfa_exec() that meant it never actually used it. Double oops. There
1057        were also very few tests of studied patterns with pcre_dfa_exec().
1058    
1059    27. If (?| is used to create subpatterns with duplicate numbers, they are now
1060        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
1061        on the other side of the coin, they are no longer allowed to have different
1062        names, because these cannot be distinguished in PCRE, and this has caused
1063        confusion. (This is a difference from Perl.)
1064    
1065    28. When duplicate subpattern names are present (necessarily with different
1066        numbers, as required by 27 above), and a test is made by name in a
1067        conditional pattern, either for a subpattern having been matched, or for
1068        recursion in such a pattern, all the associated numbered subpatterns are
1069        tested, and the overall condition is true if the condition is true for any
1070        one of them. This is the way Perl works, and is also more like the way
1071        testing by number works.
1072    
1073    
1074    Version 7.9 11-Apr-09
1075  ---------------------  ---------------------
1076    
1077  1.  When building with support for bzlib/zlib (pcregrep) and/or readline  1.  When building with support for bzlib/zlib (pcregrep) and/or readline
1078      (pcretest), all targets were linked against these libraries. This included      (pcretest), all targets were linked against these libraries. This included
1079      libpcre, libpcreposix, and libpcrecpp, even though they do not use these      libpcre, libpcreposix, and libpcrecpp, even though they do not use these
1080      libraries. This caused unwanted dependencies to be created. This problem      libraries. This caused unwanted dependencies to be created. This problem
1081      has been fixed, and now only pcregrep is linked with bzlib/zlib and only      has been fixed, and now only pcregrep is linked with bzlib/zlib and only
1082      pcretest is linked with readline.      pcretest is linked with readline.
1083    
1084  2.  The "typedef int BOOL" in pcre_internal.h that was included inside the  2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
1085      "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been      "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
1086      moved outside it again, because FALSE and TRUE are already defined in AIX,      moved outside it again, because FALSE and TRUE are already defined in AIX,
1087      but BOOL is not.      but BOOL is not.
1088    
1089  3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and  3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
1090      PCRE_MATCH_LIMIT_RETURSION values as ints, when they should be long ints.      PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
1091    
1092  4.  The pcregrep documentation said spaces were inserted as well as colons (or  4.  The pcregrep documentation said spaces were inserted as well as colons (or
1093      hyphens) following file names and line numbers when outputting matching      hyphens) following file names and line numbers when outputting matching
1094      lines. This is not true; no spaces are inserted. I have also clarified the      lines. This is not true; no spaces are inserted. I have also clarified the
1095      wording for the --colour (or --color) option.      wording for the --colour (or --color) option.
1096    
1097  5.  In pcregrep, when --colour was used with -o, the list of matching strings  5.  In pcregrep, when --colour was used with -o, the list of matching strings
1098      was not coloured; this is different to GNU grep, so I have changed it to be      was not coloured; this is different to GNU grep, so I have changed it to be
1099      the same.      the same.
1100    
1101  6.  When --colo(u)r was used in pcregrep, only the first matching substring in  6.  When --colo(u)r was used in pcregrep, only the first matching substring in
1102      each matching line was coloured. Now it goes on to look for further matches      each matching line was coloured. Now it goes on to look for further matches
1103      of any of the test patterns, which is the same behaviour as GNU grep.      of any of the test patterns, which is the same behaviour as GNU grep.
1104    
1105    7.  A pattern that could match an empty string could cause pcregrep to loop; it
1106        doesn't make sense to accept an empty string match in pcregrep, so I have
1107        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
1108        seems to be how GNU grep behaves.
1109    
1110    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
1111        start or after a newline", because the conditional assertion was not being
1112        correctly handled. The rule now is that both the assertion and what follows
1113        in the first alternative must satisfy the test.
1114    
1115    9.  If auto-callout was enabled in a pattern with a conditional group whose
1116        condition was an assertion, PCRE could crash during matching, both with
1117        pcre_exec() and pcre_dfa_exec().
1118    
1119    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
1120        used for matching.
1121    
1122    11. Unicode property support in character classes was not working for
1123        characters (bytes) greater than 127 when not in UTF-8 mode.
1124    
1125    12. Added the -M command line option to pcretest.
1126    
1127    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
1128    
1129    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
1130    
1131    16. Added comments and documentation about mis-use of no_arg in the C++
1132        wrapper.
1133    
1134    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
1135        from Martin Jerabek that uses macro names for all relevant character and
1136        string constants.
1137    
1138    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
1139        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
1140        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
1141        these, but not everybody uses configure.
1142    
1143    19. A conditional group that had only one branch was not being correctly
1144        recognized as an item that could match an empty string. This meant that an
1145        enclosing group might also not be so recognized, causing infinite looping
1146        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
1147        with the subject "ab", where knowledge that the repeated group can match
1148        nothing is needed in order to break the loop.
1149    
1150    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
1151        exec(), but without supplying a callout function, matching went wrong.
1152    
1153    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
1154        leak if the size of the offset vector was greater than 30. When the vector
1155        is smaller, the saved offsets during recursion go onto a local stack
1156        vector, but for larger vectors malloc() is used. It was failing to free
1157        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
1158        error, in fact).
1159    
1160    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
1161        heapframe that is used only when UTF-8 support is enabled. This caused no
1162        problem, but was untidy.
1163    
1164    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
1165        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
1166        included within another project.
1167    
1168    24. Steven Van Ingelgem's patches to add more options to the CMake support,
1169        slightly modified by me:
1170    
1171          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
1172              not building pcregrep.
1173    
1174          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
1175              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
1176    
1177    25. Forward references, both numeric and by name, in patterns that made use of
1178        duplicate group numbers, could behave incorrectly or give incorrect errors,
1179        because when scanning forward to find the reference group, PCRE was not
1180        taking into account the duplicate group numbers. A pattern such as
1181        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
1182    
1183    26. Changed a few more instances of "const unsigned char *" to USPTR, making
1184        the feature of a custom pointer more persuasive (as requested by a user).
1185    
1186    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
1187        pcretest.c, inside #ifndefs, because it seems they are sometimes already
1188        pre-defined.
1189    
1190    28. Added support for (*UTF8) at the start of a pattern.
1191    
1192    29. Arrange for flags added by the "release type" setting in CMake to be shown
1193        in the configuration summary.
1194    
1195    
1196  Version 7.8 05-Sep-08  Version 7.8 05-Sep-08
1197  ---------------------  ---------------------

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